Thus, tumors arising in our Chx10-Cre; Rblox/lox; p107−/−; Ptenlox/lox mice are similar to previous mouse retinoblastomas in that they also predominantly reflect amacrine and horizontal cell types but they also differ in that they contain ganglion cells but few Müller glia cells. The gene discussed is VSX2; the disease is retinoblastoma.